This invention relates to machines for making non-woven bonded carpeting by forming a plurality of accordion-like chains of yarn between two backing layers and then severing the yarn between the layers to form two carpets and, more particularly, to the portion of such a machine that cuts or severs the yarn.
Machines have been developed for making carpeting by folding a number of strands of yarn in a row simultaneously and planting them in a layer of adhesive spread across the surface of a sheet of backing material, and then repeating the operation on an opposing parallel sheet of backing material. This is done to form a series of accordion-type loops from each strand of yarn so that a plurality of lengths of material are bonded between the backing layers. After the adhesive has been cured, the loops are severed midway between the backing layers to form two separate carpets. Alternatively, individual lengths of yarn can be severed and one end planted in an adhesive coating on one backing layer and then another backing layer can be applied later to the other ends. Another type of machine has been developed in which the loops of yarn are formed initially without bonding them to the backing layers, and adhesive is applied later to the yarn.
In these types of operations, the adhesive can be used as the backing layer in addition to being the means for anchoring the yarn in place.
When a backing material is used, it is normally formed of woven strands of jute, although there are many other suitable types of backing material. The bonding material can be an adhesive such as a liquid synthetic resin which has been applied to the backing sheets or directly to the yarn. Polyvinylchloride (PVC) has been found to be effective.
After the strands of yarn are bonded to the parallel backing layers to form what is known as a yarn "sandwich," the strands of yarn must be severed at some point between the two backing layers to form the carpets. Different types of cutting mechanisms have been used in prior art machines but they have proved to be less than satisfactory. Most of these mechanisms are designed and operate in such a way that the speed at which the machine can operate is limited. Other cutters are not capable of cutting a precisely straight path across the entire width of the sandwich, which can be upward of twenty feet.
I have developed a cutter which effectively solves the above problems, which is the subject of my U.S. Pat. application No. 315,845, filed Dec. 18, 1972, now abandoned. This cutter comprises two or more blades which moves back and forth across the advancing yarn strands, each blade cutting less than the full carpet width. However, I have found that cutters which move with this back and forth action to sever the strands from side-to-side cause a "J-cut;" that is, one point on each severed yarn end sticks up higher than the rest of the end. In order to produce acceptable commercial carpeting, an additional trimming step is then required to flatten the yarn ends, which adds significantly to the cost of the carpets through additional time and equipment and wasted yarn.
Another drawback of that cutter described in my application mentioned above is that although it is significantly faster than known prior art cutters, it is still too slow for optimum operation in conjunction with the faster yarn folding mechanisms that are being developed, such as the one shown and described in my U.S. Pat. application Ser. No. 323,440, filed Jan. 15, 1973, U.S. Pat. No. 3,915,789. In addition, because of the non-continuous back and forth movement of that cutter parts tend to wear out relatively fast and a complicated and bulky moving mechanism is required which is expensive to manufacture and maintain.